We don't have a "precedent" in a settlement, you have a precedent with a win in court.
T-Mobile never denied that they are using the technology. As I recall, they used what is known as an affirmative defense. In essence they said "yeah, we are using your technology, but you have no power to enforce it because your patent is no good". Don't remember all the reasons they gave. My guess is those reasons were what was behind DSU's rant.
In any case, a settlement will not decide that the patent is valid, only a court decision that the patent is valid can preclude any other infringer from raising the exact same defense.